The long-term objective of this study is to help understand the impact patients in early stages of HIV infection have on health service delivery systems. The specific objective of this study is to assess the 1990-2 direct medical care costs and utilization of an estimated 250 patients at Group Health Cooperative of Puget Sound (GHC) who are HIV positive and are actively receiving treatment. Since the management of HIV positive patients has shifted to more treatment during the asymptomatic and mildly symptomatic early stages of the infection, existing cost and utilization studies which focus only on pre-Class IV HIV conditions (frank AIDS) no longer give a complete picture of HIV-related care. A non-experimental control group design will be used for the analysis. Cost and utilization data from the study sample will be compared for pre- Class IV patients and two control groups (all of GHC's enrollees who do not have HIV/AIDS conditions and are within the same age range as the study and Class IV HIV (AIDS) enrollees. Since all the utilization and cost variables are continuous, a linear regression analysis will be used to determine each group;s cost function. The independent variables are the costs of services (i.e., radiology, laboratory, pharmacy, hospital days, long-term care days, etc.) and the dependent variable is total cost. The cost for each service will be calculated by multiplying the utilization by the standard GHC cost for each service. GHC's accounting system allows tracking of variable and overhead costs of each service for each patient. A cross-sectional time series analysis will be used to predict the increase in cost and utilization of services attributable to HIV infection from identified HIV infection through Class IV stage to death. The analysis will characterize how the distribution of services changes with the progression of the disease, and how services compare with those utilized by age/sex matched control groups.